/*	$OpenBSD: base64.c,v 1.5 2006/10/21 09:55:03 otto Exp $	*/

/*
 * Copyright (c) 1996 by Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 */

/*
 * Portions Copyright (c) 1995 by International Business Machines, Inc.
 *
 * International Business Machines, Inc. (hereinafter called IBM) grants
 * permission under its copyrights to use, copy, modify, and distribute this
 * Software with or without fee, provided that the above copyright notice and
 * all paragraphs of this notice appear in all copies, and that the name of IBM
 * not be used in connection with the marketing of any product incorporating
 * the Software or modifications thereof, without specific, written prior
 * permission.
 *
 * To the extent it has a right to do so, IBM grants an immunity from suit
 * under its patents, if any, for the use, sale or manufacture of products to
 * the extent that such products are used for performing Domain Name System
 * dynamic updates in TCP/IP networks by means of the Software.  No immunity is
 * granted for any product per se or for any other function of any product.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE.  IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL,
 * DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE, EVEN
 * IF IBM IS APPRISED OF THE POSSIBILITY OF SUCH DAMAGES.
 */

/* OPENBSD ORIGINAL: lib/libc/net/base64.c */


#if (!defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP)) || (!defined(HAVE_B64_PTON) && !defined(HAVE___B64_PTON))

#include <sys/types.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <ctype.h>
#include <stdio.h>

#include <stdlib.h>
#include <string.h>

#include "base64.h"

static const char Base64[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static const char Pad64 = '=';

/* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
 The following encoding technique is taken from RFC 1521 by Borenstein
 and Freed.  It is reproduced here in a slightly edited form for
 convenience.
 
 A 65-character subset of US-ASCII is used, enabling 6 bits to be
 represented per printable character. (The extra 65th character, "=",
 is used to signify a special processing function.)
 
 The encoding process represents 24-bit groups of input bits as output
 strings of 4 encoded characters. Proceeding from left to right, a
 24-bit input group is formed by concatenating 3 8-bit input groups.
 These 24 bits are then treated as 4 concatenated 6-bit groups, each
 of which is translated into a single digit in the base64 alphabet.
 
 Each 6-bit group is used as an index into an array of 64 printable
 characters. The character referenced by the index is placed in the
 output string.
 
 Table 1: The Base64 Alphabet
 
 Value Encoding  Value Encoding  Value Encoding  Value Encoding
 0 A            17 R            34 i            51 z
 1 B            18 S            35 j            52 0
 2 C            19 T            36 k            53 1
 3 D            20 U            37 l            54 2
 4 E            21 V            38 m            55 3
 5 F            22 W            39 n            56 4
 6 G            23 X            40 o            57 5
 7 H            24 Y            41 p            58 6
 8 I            25 Z            42 q            59 7
 9 J            26 a            43 r            60 8
 10 K            27 b            44 s            61 9
 11 L            28 c            45 t            62 +
 12 M            29 d            46 u            63 /
 13 N            30 e            47 v
 14 O            31 f            48 w         (pad) =
 15 P            32 g            49 x
 16 Q            33 h            50 y
 
 Special processing is performed if fewer than 24 bits are available
 at the end of the data being encoded.  A full encoding quantum is
 always completed at the end of a quantity.  When fewer than 24 input
 bits are available in an input group, zero bits are added (on the
 right) to form an integral number of 6-bit groups.  Padding at the
 end of the data is performed using the '=' character.
 
 Since all base64 input is an integral number of octets, only the
 -------------------------------------------------                       
 following cases can arise:
 
 (1) the final quantum of encoding input is an integral
 multiple of 24 bits; here, the final unit of encoded
 output will be an integral multiple of 4 characters
 with no "=" padding,
 (2) the final quantum of encoding input is exactly 8 bits;
 here, the final unit of encoded output will be two
 characters followed by two "=" padding characters, or
 (3) the final quantum of encoding input is exactly 16 bits;
 here, the final unit of encoded output will be three
 characters followed by one "=" padding character.
 */

#if !defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP) 
int
b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize)
{
	size_t datalength = 0;
	u_char input[3];
	u_char output[4];
	u_int i;
    
	while (2 < srclength) {
		input[0] = *src++;
		input[1] = *src++;
		input[2] = *src++;
		srclength -= 3;
        
		output[0] = input[0] >> 2;
		output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
		output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
		output[3] = input[2] & 0x3f;
        
		if (datalength + 4 > targsize)
			return (-1);
		target[datalength++] = Base64[output[0]];
		target[datalength++] = Base64[output[1]];
		target[datalength++] = Base64[output[2]];
		target[datalength++] = Base64[output[3]];
	}
    
	/* Now we worry about padding. */
	if (0 != srclength) {
		/* Get what's left. */
		input[0] = input[1] = input[2] = '\0';
		for (i = 0; i < srclength; i++)
			input[i] = *src++;
        
		output[0] = input[0] >> 2;
		output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
		output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
        
		if (datalength + 4 > targsize)
			return (-1);
		target[datalength++] = Base64[output[0]];
		target[datalength++] = Base64[output[1]];
		if (srclength == 1)
			target[datalength++] = Pad64;
		else
			target[datalength++] = Base64[output[2]];
		target[datalength++] = Pad64;
	}
	if (datalength >= targsize)
		return (-1);
	target[datalength] = '\0';	/* Returned value doesn't count \0. */
	return (datalength);
}
#endif /* !defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP) */

#if !defined(HAVE_B64_PTON) && !defined(HAVE___B64_PTON)

/* skips all whitespace anywhere.
 converts characters, four at a time, starting at (or after)
 src from base - 64 numbers into three 8 bit bytes in the target area.
 it returns the number of data bytes stored at the target, or -1 on error.
 */

int
b64_pton(char const *src, u_char *target, size_t targsize)
{
	u_int tarindex, state;
	int ch;
	char *pos;
    
	state = 0;
	tarindex = 0;
    
	while ((ch = *src++) != '\0') {
		if (isspace(ch))	/* Skip whitespace anywhere. */
			continue;
        
		if (ch == Pad64)
			break;
        
		pos = strchr(Base64, ch);
		if (pos == 0) 		/* A non-base64 character. */
			return (-1);
        
		switch (state) {
            case 0:
                if (target) {
                    if (tarindex >= targsize)
                        return (-1);
                    target[tarindex] = (pos - Base64) << 2;
                }
                state = 1;
                break;
            case 1:
                if (target) {
                    if (tarindex + 1 >= targsize)
                        return (-1);
                    target[tarindex]   |=  (pos - Base64) >> 4;
                    target[tarindex+1]  = ((pos - Base64) & 0x0f)
                    << 4 ;
                }
                tarindex++;
                state = 2;
                break;
            case 2:
                if (target) {
                    if (tarindex + 1 >= targsize)
                        return (-1);
                    target[tarindex]   |=  (pos - Base64) >> 2;
                    target[tarindex+1]  = ((pos - Base64) & 0x03)
                    << 6;
                }
                tarindex++;
                state = 3;
                break;
            case 3:
                if (target) {
                    if (tarindex >= targsize)
                        return (-1);
                    target[tarindex] |= (pos - Base64);
                }
                tarindex++;
                state = 0;
                break;
		}
	}
    
	/*
	 * We are done decoding Base-64 chars.  Let's see if we ended
	 * on a byte boundary, and/or with erroneous trailing characters.
	 */
    
	if (ch == Pad64) {		/* We got a pad char. */
		ch = *src++;		/* Skip it, get next. */
		switch (state) {
            case 0:		/* Invalid = in first position */
            case 1:		/* Invalid = in second position */
                return (-1);
                
            case 2:		/* Valid, means one byte of info */
                /* Skip any number of spaces. */
                for (; ch != '\0'; ch = *src++)
                    if (!isspace(ch))
                        break;
                /* Make sure there is another trailing = sign. */
                if (ch != Pad64)
                    return (-1);
                ch = *src++;		/* Skip the = */
                /* Fall through to "single trailing =" case. */
                /* FALLTHROUGH */
                
            case 3:		/* Valid, means two bytes of info */
                /*
                 * We know this char is an =.  Is there anything but
                 * whitespace after it?
                 */
                for (; ch != '\0'; ch = *src++)
                    if (!isspace(ch))
                        return (-1);
                
                /*
                 * Now make sure for cases 2 and 3 that the "extra"
                 * bits that slopped past the last full byte were
                 * zeros.  If we don't check them, they become a
                 * subliminal channel.
                 */
                if (target && target[tarindex] != 0)
                    return (-1);
		}
	} else {
		/*
		 * We ended by seeing the end of the string.  Make sure we
		 * have no partial bytes lying around.
		 */
		if (state != 0)
			return (-1);
	}
    
	return (tarindex);
}

#endif /* !defined(HAVE_B64_PTON) && !defined(HAVE___B64_PTON) */
#endif 
